Illumination installation

ABSTRACT

An illumination installation, in particular for lighting a transparent table or supporting step-by-step microfilm camera apparatus, such installation providing for the even illumination of a condenser of an image projecting apparatus. A plurality of lamps are distributed over the surface to be illuminated, the lamps being divided into at least two groups. In certain embodiments the current supply circuit for feeding the lamps is divided into two parallel circuits, each of which contains a resistor, there being an amplifier which scans the voltage drop at the resistors and operates an optical and/or acoustical signal transmitter upon an unbalance of the voltage drops through the respective resistors. In another embodiment, the feeding of current to the lamps is divided into at least two parallel circuits, the passage of circuit through which is compared by a compensatory current transformer which controls a relay controlling an optical and/or acoustic signal transmitter and/or a switch controlling a further apparatus controlling circuit.

1 States; Patent" [191 .1 'Bickl'etaL' 1 11* 3,796,915 Mar. 12, 1974 [51 1 ILLUMINATION INSTALLATION [75] inventors: Horst Bickl, Munich;Joachim- Lange, Unterhaching; Heinrich Ne'uma'nn, Munich; Bernhard 1Goschin, Munich; Alois Rieder, Munich, all of Germany 73 Assignee:AGFA-Gevaert'aktiengesellschaft,

Postfach, Germany 221 Filed: Y m 4,1972

1211 Appl. No.: 250,314

g Related U. S Application Data 1 g [62] Division of sci. No.. 81,267,Oct. 16, 1970, Pat. No.

5 nt. .,...,Gosr, 1/10 1 58 Field of Search 315/130, 132, 135, 201,

- .7 ,sls zpww [56] W .Ref ereuces Clted I UNITED STATES PATENTS? 1 14." Jess-n1; 3311 1131X 3,706,983 12/1972? Olsen eti a 315/135 X PrimaryExaminer-Herman Karl Saalbach Assistant Examiner-Richard A. Rosenberger157 j 7 ABSTRACT An illumination installation, in particular forlighting a transparent table or supporting step-by-step microfilm cameraapparatus, such installation providing for the even illumination of acondenser of an image projecting apparatus. A plurality 'of lamps aredistributed over the surface to be illuminated,the lamps being dividedinto at least two groups. In certain embodiments the current supplycircuit for feeding the lamps is divided into two parallel circuits,each'of which contains a resistor, there being an amplifier which scansthe voltage drop at the resistors and operatesan optical and/oracoustical signal transmitter upon an unbalance of the voltage dropsthrough the respective resis: tors. v

In another embodiment, the feeding of current to the lamps is dividedinto at least twoparallel circuits, the

passage of circuit through which is compared by a compensatory currenttransformer which controls a relay controlling an optical and/or,acoustic signal transmitter and/or aswitch controlling a furtherapparatus controlling circuit.

3 Claims, 3 Drawing Figures ILLUMINATION INSTALLATION This is adivisional application of application Ser. No. 81,267 filed Oct. 16,1970 now US. Pat. No. 3,732,461. I

This invention concerns an illumination installation, in particular atransparent table or support for microfilm step-by-step cameras, overthe area of which several lamps are spaced for the even illumination ofa condenser of a projection device.

The transparency folios to be filmed with microfilm step-by-stepcameras, are placed on an illumination box, the so-called transparenttable, during the exposure. In order to produce an even backgrounddensity on the film, the light density of the surface must be adjustedin accordance to the decrease of light of the object photographed and inaccordance to other fixed differences in the light circuit of theimage-forming path of the rays. This happens, in general, with many ofthe single illumination lamps provided for the transparent table, suchlamps being adjustable and electrically connected to several lampgroups. The single lamp groups will in general be switched on or off insections at the filming of transparencies of different formats, withobjectives of varied focal lengths, and with different reductionfactors.

The failure of a single lamp or even a whole group of lamps as a rule isnot ascertainable by observation of the light surface of the transparentilluminating table.

The exact illumination of the film window is considerably disturbed bythe unlighted condition of one or several lamps, so that films exposedunder such conditions may become unusable. It is therefore essential todetect and to signal through a control apparatus the lack of anillumination lamp.

Galvanometer lamps, for example, are in use as control apparati; theseare switched in line with the receiver, that is, the bank ofilluminating lamps. This signal system can be applied to only a verylimited number of lamps. In any case, it leads to a relatively costlyconstruction which is hard to monitor, and is subject to interference,in particular in case of voltage regulated lamps. It is further knownthat optical signal transmitters may be used, which are controlled bymetering elements that are connected to each of the receiver circuits.In such systems, a large number of signal transmitters is essential;this makes the control system relatively costly and difficult to monitorand maintain. In view of the aforementioned regulation shifts, thesignal transmitters must be sensitive enough to react only to thecomplete cessation of function of one lamp. Changes in illuminationstrength because of changes due to heat resistance of a single lamptherefore should not be indicated. Also, the on-and-off switching ofreceivers is possible only by replacing the receiver with a commensurateresistor.

In accordance with this invention, the lamps are split up into at leasttwo lamp or receiver groups, and a comparative switching mechanism isprovided for the current flowing through these receiver circuits. As aresult, all lamp groups can be controlled by a single signal controldevice. Regulatory shifts do not enter into the measured result, so thatthe sensitivity of the signal installation can be increased, if desired.Also, an onand-off switching of the lamps is possible without theappearance of greater losses in efficiency as is more fully shown in thefollowing description.

In line with the carrying out of this invention, the feeding ofelectricity to the lamps is further divided into two parallel electriccircuits, each of which contains a variable resistor and a differenceamplifier which controls an optical and/or acoustic signal transmitter.Preferably, in addition, there is provided a switch for thesimultaneous, parallel switching-on of lamp groups.

In accordance with other forms of execution of the invention, at leasttwo of the receiver groups are switched in line and are positionedparallel to a line of measurement resistors. Both of these rows areconnected with a glow lamp. The control of several rows of lamps via asingle glow lamp is possible because several receiver rows with equalresistance relation are switched parallel, and all glow lamps areconnected to a diode. Also, with this construction, on-and-off switchingof lamp groups for the purpose of format reversal is possible, ifswitches are coupled together.

In accordance with a further embodiment, the supply of current to thelamps is apportioned into at least two parallel circuits, which controlan optical and/or acoustic signal transmitter. With this measure, asymmetrical lamp failure can be established, if the sphere of the lampis divided into asymmetrical receiver groups. Preferably, this systemincludes a transformer functioning as a compensatory currenttransformer. A relay and a transistor intensifier may be switched incircuit with this current transformer.

In this drawing, several examples of the invention are illustrated:

FIG. 1 is a wiring diagram of a system in which there is a comparison ofvoltage between two parallely switched lamp groups;

FIG. 2 shows a system in which there is a comparison of voltage betweenlamp groups and a row of resistors via a glow lamp; and

FIG. 3 shows a system in which there is a comparison of current via acompensatory current transformer.

In FIG. 1, between two main circuit wires 1 and 2 connected to asuitable source of alternating current (not shown) are positionedserially connected lamp rows G1-4, Y 1 and 2, X1 and 2 and Z. The rowsof lamps each contain ten lamps and serve for the illumination of areasof a transparent table. The lamp rows G1, G2, Y1, X are connected to acommon conductor 3 and are connected with main circuit wire 2 via wire4, a resistor M, and a wire 5. The rows of lamps G 3, G 4, X2, Y 2 and Zare connected-to a common wire 6, which is connected wire 2 through awire 7, a variable resistor M 2, and a wire 8.

The precision measuring resistors M l and M 2 (when suitably adjusted)are of equal size, so that when both lamp groups connected to theirrespective resistance show equal total resistances, there is no voltagedifference between wires 3 and 6. This is the case, if, as shown in FIG.1, both lamp rows X l and X 2, consisting of similar lamps, aresimultaneously connected to wires 1 and 2 through switch S 2.1, theasymmetrically disposed lamp row Z is switched off, and both lamp rows Y1 and Y 2 are switched off through switch S 1. With simultaneousswitching in of lamp rows Y 1 and Y 2 by switch S 1, or switching off oflamp rows X l and X 2 through switch S 2.1, no change in voltageequilibrium takes place. The switching in of the asymmetrically placedlamp row Z through switch S 2.1, however, causes the appearance of avoltage difference between wires 3 and 6. In order to avoid this, switchS 2.1 is coupled mechanically with switch S 2.2, which is connectedthrough conductors 9 and 10 to an adjustable contact 11 of variableresistor M 2, contact 11 permitting variable resistor M 2 to beby-passed to a varying degree, that is, to function as a potentiometer.

By use of switch S l, S 2.1, and S 2.2 it is also possible to switch onand off selected lamp groups with the change of the format of the objectbeing photographed, without effecting a change in the voltagestabilization of conductors 3 and 6. This voltage stabilization remainsintact even when the illumination of the lamp is adjusted through largealterations in the supply voltage. On the other hand, an immediatevoltage difference appears at wires 3 and 6, if, in either electricsupply circuit for the lamps, a lamp ceases to function, or changes itsresistance due to heat. To ascertain this voltage difference, a furthervariable resistor M 3 is employed, the adjustable contact 12 of which isconnected to one input terminal of amplifier D via wire 13. The variableresistor M 3 is connected to wire 3 through wires 15, 16 and 17 with theinterposition of a diode 18 between 16 and 17, wire 6 through a wire 19,wire 20, a diode 22, and a wire 21. The diodes l8 and 22 are oppositelydisposed, as shown, to smooth the rectified current, the terminals ofvariable resistor M 3 are also connected to main circuit wire 2 viawires 25 to 28 with the interposition of condenser 23 and 24,

respectively, as shown. A further wire 29 connects wire 2 to the otherinput terminal of amplifier D.

As soon as a voltage differential occurs between wires 3 and 6, avoltage will be picked up at variable resistor M 3: such voltage isamplified in amplifier D and conducted to an optical of acousticalsignal device S via wire 30. The other terminal of device 3 is connectedto by wire 1 by wire 31. With the use ofa sensitive amplifier D thevariable resistors M 1 and M 2 may be of correspondingly low resistance,so that only an insignificant loss of function occurs. After theexchange of all or several lamps should the output impedance of the newlamps not correspond to the exact, output impedance of both circuits, acorrespondingly changed voltage may be provided by adjustment of contact12 of resistor M 3 and by adjustment of the gain of amplifier D.

In accordance with FIG. 2, rows of series connected lamps G 5 to G 16are located between supply wires 1 and 2. The rows of series connectedlamps are each divided into 2 symmetrical halves which are connected atjunctions between both halves by respective wires 32 to 37. The rows ofseries of connected lamps G 9 to G 14 are connected to wire 1 throughswitch S 3.1; the rows of lamps G 15 and G 16 are connected to wire 1through switch S 4.1 Wires 32 and 33 are connected to a wire 42 by meansof diode 38 and 39, respectively, through wires 40 and 41. Further wires43 and 45 connect wires 34 and 36, respectively, with through diodes 46,48, respectively, and a switch S 3.2 to wire 42. Further, wire 37 isconnected to wire 42 through a diode 49 and a switch S 4.2.

One terminal of glow lamp 50 is connected to wire 42; the other terminalis connected by wire 51 to a junction between two series connected equalresistors M 4 and M 5 connected across wires 1 and 2. Resistors M 4 andM 5 may be made adjustable, if desired. Since both lamp rows as well asresistors M 4 and M 5 have an equal resistance ratio, both wires 32 and37, as well as wire 51 in normal operation operate at equal potential.Glow lamp 50 therefore is not fed any current under such condition. If,in any of the aforementioned rows of connected lamps, one lamp ceases tofunction, the corresponding point of attachment remains under thecomplete potential of the wire connected to a row of lamps as yetunaffected, while wire 51 connected between resistors M 4 and M 5remains at its original potential.

Assuming a voltage supply of 220 V, a considerable difference inpotential occurs between wire 51, connected between M 4 and M 5, andwire 42. Such difference in potential may amount to 1 10 V, which causesglow lamp 50, which may initially light at V, to light up. Diodes 38,39, 46, and 49 prevent current from travelling over the unaffectedconnecting points, which remain at the original potential, rather thanthrough the glow lamp 50. Lamp 50, however, will not be lighted byfluctuations in voltage between wires 1 and 2. Because of the glow lampusing very little current, the resistors M 4 and M 5 have highresistance values; the system therefore consumes very little electricalenergy.

The on and off switching of any lamp groups is possible without causingglow lamp 50 to light up, if at the same time the connection to eachvariable resistor to glow lamp 50 is interrupted via switches S 3.1, S3.2, S 4.1, and S 4.2, the movable contacts of which are mechanicallyinterconnected so that they operate in unison.

In the system of FIG. 3, one terminal of each of lamps Y1, Y2, G1 to G4,X1, X2, and Z is connected to wire 1. The other terminals of the lampsare selectively connected in manners to be described to various portions52-55 of the low resistance primary winding of a compensatory currenttransformer Tr. Such transformer has a magnetic core, as shown, and asecondary winding 56. Windings 52, 53, 54, and 55, have numbers of turnsin the ratio 10 5 3 3. The second terminals of parallel connected lampsY1, Y2 are connected to one terminal of an on-off switch S 5.1 the otherterminal of switch S 5.1 being connected through wire 65 to the secondterminal of lamp G1, such second terminal being connected to the firstterminal of a second, two-position switch S 5.2 which is mechanicallyinterconnected with switch S 5.1 as shown. One second terminal of switchS 5.2 is connected by a wire 66 to one end of the primary windingportion 52, the other second terminal of switch S 5.2 being connected bya wire 67 to the junction between primary winding portions.

The junction 68 between primary winding portions 53 and 55 is connectedto main wire 2. The second terminals of lamps G2, G3, and G4 areconnected to a wire 70 which leads to a first, single terminal of atwoposition switch S6. The second end of primary winding portion 55 isconnected to wire 70 by a wire 69. One second terminal of switch S6 isconnected to the second terminal of parallel connected lamps X1, X2. Theother second terminal of switch S6 is connected by wire 71 to the firstend of primary winding portion 54; the second end of winding portion 54is connected by a wire 72 to the second terminal of lamp Z.

The secondary winding 56 of the transformer Tr has the ends thereofconnected to the input of an amplifier V the output of which isconnected to the coil of a relay 57. A signal device S is connectedbetween the other terminal of switch 61 and a wire 62 which is connectedto main wire 1. The relay 57 controls a second switch 59, the movablecontactors of switches 59 and 61 being mechanically connected as shownso that when switch 59 is closed, switch 61 is open, and viceversa.Switch 59 is interposed in a further, separate circuit having leads 63,64 in which a further, manuallyoperated external switch 60 is interposedin series with switch 59. The further circuit 63, 59, 60, and 64 may beemployed to control another mechanism (not shown) of the apparatus withwhich the device of the invention is associated, or may be a part of thecurrent supply circuit powering leads 1 and 2, whereby all of the lampsare shut off when a current unbalance between the various groups oflamps occurs.

The control system of FIG. 3 functions as follows:

The switches S 5.1, S 5.2 selectively connect the lamps Y1, Y2 with allof the turns of windings 52,:53 of transformer Tr, or lamps Y1, Y2, andG1 with coil 52 of transformer Tr. The further switch S6 selectivelyconnects lamp Z with the two series connected transformer windings 54and 55, or lamps X1 and X2 with winding 55. Lamps G2 to G4 areconstantly connected to winding 55. Series connected windings 52 and 53,on the one hand, and series connected windings 54 and 55, on the otherhand, are, in effect, connected to wire 2 in the opposite direction, sothattheir reactions relative to the secondary winding 56 of transformerTr oppose each other; no current flows in transformer secondary winding56, when all windings are subjected to an equal number of ampere turnsand the resulting flux in the core of the transformer Tr is zero. Thisis always the case if the same current flows through all lamps.

Both lamp switches S 5.1, S 5.2, on the one hand, and S6, on the other,can be used independently of each other, without affecting the evennessof the number of ampere winding turns at windings 52, 53, 54, and 55.Also regulatory fluctuations of the current supply source do not enterinto such proportionalities. On the other, hand, as can be easily provedby simple computation, the constancy will be interrupted in the unlikelyinstance of cessation of lamp functions in different lamp groups occurs,due to the asymmetrical division of the number of ampere winding turns.And lastly, the transformer Tr is constructed in such a way that itslow-resistance windings are positioned in the lamp circuits, in order tominimize current consumption and to cause a relatively large change involtage with only a minor shift in current.

If the resistance of one of the lamps is altered, or if one of the lampsceases to function, a current flows in secondary winding 56; suchcurrent is intensified by amplifier V and conducted to the coil of relay57. Switches 59 and 61 are thereupon closed, signal S is actuated, andauxiliary circuit 63, 59, 60, and 64 is energized. When the current flowin secondary winding returns to zero, upon the correction of thecondition of uneven lighting, signal S is de-energized and the auxiliarycircuit is opened.

Although the invention is illustrated and described with reference to aplurality of embodiments thereof, it is to be expressly understood thatit is in no way limited to the disclosure of such a plurality ofpreferred embodiments, but is capable of numerous modifications withinthe scope of the appended claims.

We claim:

1. In a uniform illumination system:

a source of energizing voltage;

at least two first paths each comprising a plurality of seriallyconnected lamps;

a second path comprising a pair of serially connected resistors;

first means for coupling the first paths and the second path across thesource;

a glow lamp; and

second means for coupling the glow lamp between the junction of theresistors and the midpoint of each of the first paths, each suchmidpoint dividing the resistance of the associated first path in half.

2. A system as defined in claim 1, in which the second means comprises aplurality of similarly poled diodes individually associated with themidpoint of each first path. I

3. A system as defined in claim 2, in which the apparatus has threefirst paths; in which the first coupling means comprises, incombination, means for directly connecting two of the first paths acrossthe source, and first normally unoperated switching means operable toconnect the remaining first path across the source; and in which thesecond coupling means further comprises, in combination, means fordirectly connecting said two first paths to the glow lamp through theirassociated dioded, and second normally unoperated switching meansoperable in synchronism with the first switching means for connectingsaid remaining first path to the glow lamp through its associated diode.

1. In a uniform illumination system: a source of energizing voltage; atleast two first paths each comprising a plurality of serially connectedlamps; a second path comprising a pair of serially connected resistors;first means for coupling the first paths and the second path across thesource; a glow lamp; and second means for coupling the glow lamp betweenthe junction of the resistors and the midpoint of each of the firstpaths, each such midpoint dividing the resistance of the associatedfirst path in half.
 2. A system as defined in claim 1, in which thesecond means comprises a plurality of similarly poled diodesindividually associated with the midpoint of each first path.
 3. Asystem as defined in claim 2, in which the apparatus has three firstpaths; in which the first coupling means comprises, in cOmbination,means for directly connecting two of the first paths across the source,and first normally unoperated switching means operable to connect theremaining first path across the source; and in which the second couplingmeans further comprises, in combination, means for directly connectingsaid two first paths to the glow lamp through their associated dioded,and second normally unoperated switching means operable in synchronismwith the first switching means for connecting said remaining first pathto the glow lamp through its associated diode.